Battery packs in each of which a plurality of batteries are housed in a case so as to output a predetermined voltage and have a predetermined capacity are widely used as power sources for various equipment and vehicles. For these batteries packs, a technique of connecting general-purpose batteries in parallel or in series to form modules of battery assemblies each outputting a predetermined voltage and having a predetermined capacity and of variously combining such battery modules to cope with various applications. This module technique enables reduction in size and weight of battery modules by enhancing performance of batteries housed in battery modules, and therefore, has advantages such as improved workability in packaging battery packs and high flexibility in installing battery modules in limited space of vehicles or the like.
On the other hand, as the performance of batteries housed in battery modules has been enhanced, it has become more and more important to increase the safety of batteries modules as groups of batteries as well as the safety of batteries themselves. In particular, in a situation where a gas is generated by heat due to, for example, an internal short circuit in a battery and a safety valve actuates to release a high-temperature gas to outside the battery, when adjacent batteries are exposed to this high-temperature gas, normal batteries might also be affected, resulting in the possibility of a secondary degradation influenced by the abnormal battery.
To solve this problem, Patent Document 1 shows a power source device including a release mechanism in which a case housing a plurality of batteries is divided by a partition into a battery space housing the batteries and a release space through which a high-temperature gas from the batteries is released and in which openings of safety valves of the batteries communicate with an exhaust room. This configuration of the release mechanism allows a high-temperature gas from the safety valves of the batteries to flow into the exhaust space while preventing the high-temperature gas from flowing into the battery space, and to be released to outside the case through an outlet of the case. In this manner, it is possible to prevent adjacent batteries from being exposed to a high-temperature gas from an abnormal battery, thereby reducing a harmful influence on normal batteries.